The summer is hot, the water warm and people hoping to enjoy a pleasant day on Wisconsin’s lakes and rivers are instead turned away — disgusted at the soupy green blooms appropriately nicknamed pond scum.

This is peak season for algae blooms, including toxic blue-green algae.(Photo: J. Val Klump)

But besides its distasteful appearance, there are real health and environmental risks, as a North Carolina couple found out last week when their three dogs died from exposure to toxic blue-green algae.

Also known as cyanobacteria, blue-green algae has been around for millions of years. But its blooms and subsequent health concerns for humans and our pets — which can arise from just a simple brush with the stuff — are getting more frequent as the planet warms.

The state Department of Natural Resources says it's difficult to say whether weather conditions and other factors mean an increase in blue-green algae this summer over past years.

"To be honest, it's really hard to know for sure," said Gina LaLiberte, the statewide blue-green algae coordinator for the DNR.

Wisconsin does not have enough long-term data to chart the ups and downs, according to LaLiberte.

Also, blue-green algae can be "patchy," she said, meaning that one part of a lake can be riddled with heavy concentrations and another part of the lake is not.

"I will say there is worldwide evidence that a lot of changing weather patterns due to climate change are increasing the prevalence of blooms and we are possibly seeing that in Wisconsin," LaLiberte said.

Here’s what you should know.

When in doubt, get out

If the water looks iffy or if signs are posted, avoid swimming or other activities, according to LaLiberte.

Though the toxins in blue-green algae can cause a rash on human skin, ingesting it leads to more serious illness, LaLiberte said. Even water skiing or tubing on an algae-filled lake can cause people to inhale droplets that could make them sick.

If you’re looking to be in the water, pick the best, clearest conditions you can, especially if you’ve got a child or pet in tow. And if your dogs jump in to swim, make sure to wash them afterward to remove algae — don't just use a towel.

“If the water looks like something a human wouldn’t want in his or her mouth, then probably the dogs shouldn’t be in it either,” LaLiberte said. “Dogs are going to be really willing to drink that lake.”

Humans or pets experiencing stomach cramps, seizures, vomiting, fever, muscle weakness or other symptoms related to the algae should contact a doctor immediately, according to the DNR website.

It’s linked to recent animal deaths in Wisconsin

Blue-green algae made the news last week when three dogs in North Carolina died after swimming in a pond that contained the toxins. In Wisconsin, the state Department of Health said the algae was possibly related to three cattle deaths last year.

DHS is the agency that tracks algae-related illness reports, not the DNR. It became a reportable condition in July 2018, and people can submit those reports in an online survey or to the Wisconsin Poison Center.

Preliminary results for 2019 show five blue-green algae illness complaints, two of which were found to be unrelated to the algae, said DHS communications specialist Jennifer Miller. In 2018, the department received 25 complaints involving 24 human and nine animal illnesses. Fifteen of those complaints were found to be possibly related to the algae.

A dog death that was reported this year was deemed not to be related to blue-green algae, Miller said.

It’s harder on the water than ‘true algae’

Not all algae is toxic, even if it is pretty gross-looking.

True algae, also known as green algae, looks like long green hair in the water, LaLiberte said. This algae isn’t harmful and actually is an important part of the ecosystem of a water body, serving as high-quality food for its inhabitants to eat.

Blue-green algae is present in most waterways. But in a superconcentrated bloom, it poses serious health threats.

True algae is easily confused with its more harmful counterpart — so if you’re not sure, just skip it.

Climate change could make it worse

The effects of a warming planet will likely cause these algal blooms to happen more often, more intensely and in more bodies of water, according to the U.S. Environmental Protection Agency.

Wisconsin is already seeing it, LaLiberte said, as intense single-day rains produce more nutrient-rich runoff into bodies of water. More nutrients spur more bloom growth. Hotter temperatures mean even more blooms since they grow better in warmer water, she said.

Though structural changes are needed to address climate change on a broader level, LaLiberte said everyone can play a part in battling the blooms. Wisconsin farmers are leading initiatives to improve soil health, she said, and people living on lakes can check their septic systems regularly to ensure they’re running correctly and create a natural buffer system at their shoreline, not just grass.

In Green Bay, it’s being tracked from space

The city of Green Bay’s wastewater utility, NEW Water, in May became part of a NASA initiative that uses satellite images to track changes in the bay’s water color.

They placed a device called SeaPRISM on one of the wastewater utility’s monitoring stations in the bay, the Fox River and the East River. The device refines data collected by the satellite images to determine the effects that algae has on the bay, which has struggled with the blooms for years.

Green Bay is one of just three freshwater bodies in the U.S. that are part of this initiative. The others are in Florida and California.

“This program incorporates collaboration and innovation,” Thomas Sigmund, NEW Water executive director, said when the partnership was announced. “Both are needed to solve the complex water issues of our era.”